De La Peña Silva, A. J. .; Pérez Delgado, R. .; Yepes Barreto, I. .; De La Peña Martínez, M. . Is Visual Estimation Useful in Determining the Extent of Perioperative Haemorrhage? A Study of Correlation Among Anaesthetists of Intermediate and High Complexity Hospitals in Cartagena, Colombia. Colomb. J. Anesthesiol. 2014, 42, 247-254.